This invention relates to monolithic refractory linings in process vessels and equipment such as reactors, conduits, furnaces, incinerators and the like and, more particularly, to anchors for reinforcing and protecting refractory linings from erosion.
Refractory liners have been used for many years in process vessels, reactors, conduits, furnaces and the like to provide thermal insulation and in environments such as fluidized catalytic reactors, regenerators, or stacks, to provide resistance to abrasion and erosion. Refractory liners not only serve to thermally insulate a vessel, but also prolong the useful life of the vessel by shielding it from erosion and abrasion. In fluid catalytic cracking units for petroleum hydrocarbons, the abrasive effect of entrained cracking catalyst is very pronounced because of high fluid velocities on the order of 50 to 150 ft/second. High temperatures also occur in both the fluid bed reactor and the regenerator. For example, in the reactor the temperature may be 800.degree.-1100.degree. F. In the regenerator, the temperature of gases exiting through the cyclones may be on the order of 1250.degree.-1450.degree. F. It has been the usual practice to line vessels, conduits and cyclone separators, through which fluid with entrained catalyst flows, with refractory liner to prevent erosion of the metal surfaces and to provide thermal insulation. The refractory liner can be a refractory cement, or concrete.
In order to retain the refractory, various anchoring arrangements have been employed. U.S. Pat. No. 3,076,481 to Wygant, which is hereby incorporated by reference, describes many of the problems involved in anchoring refractory concrete linings and of a particular anchorage arrangement.
Heretofore, a preferred anchorage arrangement which provided some erosion protection was the use of hexagonal steel grating which was welded to the vessel or conduit wall. The refractory was deposited in the hexagonal spaces defined by the hexagonal grating. The hexagonal grating provided the desired erosion resistance for the refractory by projecting to the exposed surface of the refractory. The many disadvantages of hexagonal grating, however, are its relatively high cost, lack of flexibility which makes it difficult to apply to curved surfaces, its tendency to separate from the vessel or conduit wall over relatively large areas when welds fail, and its unsuitability for use with fiber reinforced refractories or with refractory concretes containing coarse aggregate particles.
In situations where hexagonal grating is not suitable, weldable studs, such as those described in U.S. Pat. No. 3,657,851 to Chambers et al and U.S. Pat. No. 3,336,712 to Bartley, have been proposed. Such studs are suitable for use with fiber reinforced refractory or with refractory concrete but do not provide erosion protection for the refractory.
Over the years, a number of refractory anchors and other devices have been suggested. Typifying these prior art refractory anchors and other devices are those shown in U.S. Pat. Nos. 78,167; 1,624,386; 2,340,176; 2,479,476; 3,076,481; 3,177,619; 3,424,239; 3,429,094; 3,449,084; 3,500,728; 3,564,799; and 3,587,198. These prior art refractory anchors and other devices have met with varying degrees of success.
It is therefore desirable to provide an improved refractory anchor which overcomes most, if not all, of the above problems.